1. Field of the Invention
The present invention relates generally to an apparatus and system for providing rapid hot water on-demand from a source, such as a water heater or boiler, to a point of use, such as the tap of a sink in a potable water system.
2. Description of the Prior Art
The present invention has application for homes, industrial or commercial buildings, or other structures having water lines which convey water from a source of hot water to an ultimate point of use, such as a kitchen or lavatory sink, a tub or shower, or other tap for dispensing hot water. Many existing structures have hot and cold water lines which discharge at a point of use with the discharge being controlled by a manual faucet in each line, or through a blending faucet common to both lines. The discharged water then passes down a discharge drain to the sewer system. In a typical residential, industrial or commercial installation, the water lines are contained in walls or flooring and distribute water to various commonly known discharge points. The water heater or boiler which supplies the hot water to the system is often located on the order of 10 to 150 feet or more from the various discharge points.
A common problem with potable water systems of the type described having an associated hot water source is that once the tap, valve or faucet controlling the flow of the water from the heated source is turned off, the water which is left in the line between the valve and the water heater or boiler gradually cools over time. The hot water line will lose heat in accordance with a number of variables, such as the nature of the conduit material conveying the water, the surrounding insulation, the temperature differential with the ambient surroundings, and the length of the line from the hot water source to the point of use where it is discharged. If a sufficient amount of time has elapsed before the hot water from that tap is again required, the user must wait until the cooled water within the line is evacuated through the lavatory drain and the hot water line is once again filled with hot water. The problem is usually worse in the case of large, single story homes, which tend to be more spread out than multilevel homes, where the water heater can be great distances from the farthest tap. A user may be forced to wait several minutes for the cooled water in the line to evacuate before hot water arrives at the tap location. The same process is repeated over and over during a typical day as water is allowed to cool again prior to repeated usage.
A number of different solutions to the above problem have been suggested in order to provide hot water rapidly at remote taps from the water heating device. One such solution is a recirculating system in which a return line is plumbed from the most remote tap back to the water heater source with a recirculating pump installed to provide a continuous flow of water. The flow ensures a supply of warm water contained in the plumbed line so that whenever the tap is turned on, warm water flows. There are a number of drawbacks with such a system, however. There is typically a relatively large up-front cost in installing such a system. It is usually necessary that the system be installed as a part of new construction. In other words, it is not easy to retrofit existing structures with circulating or recirculating systems. It is difficult or impossible to adequately insulate such systems in order to avoid unnecessary energy loss. In addition to the return line, an electrical pump is usually installed. The pump must be maintained and is subject to failures. In addition, there is an increase in electrical costs associated with the pump and the additional load on the water heater.
Another proposed solution for the problem of supplying rapid hot water is to provide a “point source” instant hot water device. Such devices are typically installed directly below the tap where the hot water is desired. The supplemental point source heating device is typically powered by an AC electric power source and is relatively expensive to install. The point source device usually has a small storage capacity of only a few gallons. The heat source is typically a resistance heating element, making such systems inefficient and expensive to operate in terms of relative energy costs.
Another more exotic solution to the problem is the so-called “convective circulating loop.” These type systems operate on the principal that in a closed recirculating flow loop, warm water will rise and cool water will fall, providing a continuous recharge of warmed water into the loop, from which taps and valves are operated. In this type system, a return loop segment is run from the farthest hot water tap back to the water heater. A venturi is typically provided to initiate flow, and a check valve is included to prevent back flow of water in the return line when the cold tap is operated. The plumbed return loop enters the cold water line just before the water heater device. However, there are also known drawbacks with the convective circulating loop type system. In order to operate, the return loop must be above the water heater. This generally limits the use of such systems to multi-story homes or buildings with the plumbing occurring above the level of the heated water source. If the system is installed in a typical one-story slab home with the potable water plumbing installed through the slab, then the necessary rise of warmed water and fall of cooled water will not take place. Another disadvantage of the system is the cost of running the return loop line in an existing home, typically limiting the application to professional plumbers. Again it is difficult to adequately insulate such systems and they tend to be relatively expensive from an energy point of view to operate.
To summarize, the most commonly used prior art systems, of the type described, are all relatively costly to purchase, install and operate in terms of energy costs. All typically require the services of a professional plumber for installation. The first two systems typically require an AC power source to operate, and the third system requires the plumbing to be above the heated water source to operate.
An object of the present invention is to provide a system for supplying rapid hot water on-demand at a point of use, which system is easy to install, relatively economical to purchase, and which can be operated from a DC power source, such as a battery source, if desired.
Another object of the present invention is to provide a system for supplying rapid hot water on-demand at a point of use, which system is easy to install, relatively economical to purchase, and which can be operated from an AC power source if desired.
Another object is to provide such a system which does not require that the presence of a return loop which is located at an elevation above the level of the heated water source.
Another object of the invention is to provide a system for supplying rapid hot water on-demand at a point of use where the system can be easily installed, for example, at a location below a lavatory sink associated with a discharge tap using simple tools and with a minimum of trouble or expense.
Another object of the invention is to provide such a system which can be easily installed by a homeowner without the necessity of employing a professional plumber.
Another object is to provide such a system which can be easily and economically installed by a home builder during new home construction, including hard wiring the system for AC power, in order to provide rapid hot water in the home with little additional expense to the ultimate home purchaser.